CN102132537A - Method of estimating the quality of focusing of a signal pre-equalized by time reversal - Google Patents

Method of estimating the quality of focusing of a signal pre-equalized by time reversal Download PDF

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CN102132537A
CN102132537A CN2009801331742A CN200980133174A CN102132537A CN 102132537 A CN102132537 A CN 102132537A CN 2009801331742 A CN2009801331742 A CN 2009801331742A CN 200980133174 A CN200980133174 A CN 200980133174A CN 102132537 A CN102132537 A CN 102132537A
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signal
antenna
focus
communication entity
aggregate quality
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CN102132537B (en
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迪恩·T·法恩休伊
乔·威亚特
尤姆尼·齐亚德
让-菲利普·德斯巴特
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France Telecom SA
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L25/00—Baseband systems
    • H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
    • H04L25/0202—Channel estimation
    • H04L25/0212—Channel estimation of impulse response
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B17/00—Monitoring; Testing
    • H04B17/30—Monitoring; Testing of propagation channels
    • H04B17/309—Measuring or estimating channel quality parameters
    • H04B17/318—Received signal strength
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L1/00—Arrangements for detecting or preventing errors in the information received
    • H04L1/0001—Systems modifying transmission characteristics according to link quality, e.g. power backoff
    • H04L1/0023—Systems modifying transmission characteristics according to link quality, e.g. power backoff characterised by the signalling
    • H04L1/0026—Transmission of channel quality indication
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L25/00—Baseband systems
    • H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
    • H04L25/0202—Channel estimation
    • H04L25/0224—Channel estimation using sounding signals
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L25/00—Baseband systems
    • H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
    • H04L25/03—Shaping networks in transmitter or receiver, e.g. adaptive shaping networks
    • H04L25/03006—Arrangements for removing intersymbol interference
    • H04L25/03012—Arrangements for removing intersymbol interference operating in the time domain
    • H04L25/03019—Arrangements for removing intersymbol interference operating in the time domain adaptive, i.e. capable of adjustment during data reception
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L25/00—Baseband systems
    • H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
    • H04L25/03—Shaping networks in transmitter or receiver, e.g. adaptive shaping networks
    • H04L25/03006—Arrangements for removing intersymbol interference
    • H04L25/03343—Arrangements at the transmitter end
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B17/00—Monitoring; Testing
    • H04B17/20—Monitoring; Testing of receivers
    • H04B17/27—Monitoring; Testing of receivers for locating or positioning the transmitter
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L25/00—Baseband systems
    • H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
    • H04L25/03—Shaping networks in transmitter or receiver, e.g. adaptive shaping networks
    • H04L25/03006—Arrangements for removing intersymbol interference
    • H04L2025/0335—Arrangements for removing intersymbol interference characterised by the type of transmission
    • H04L2025/03426—Arrangements for removing intersymbol interference characterised by the type of transmission transmission using multiple-input and multiple-output channels
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L25/00—Baseband systems
    • H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
    • H04L25/03—Shaping networks in transmitter or receiver, e.g. adaptive shaping networks
    • H04L25/03006—Arrangements for removing intersymbol interference
    • H04L2025/03777—Arrangements for removing intersymbol interference characterised by the signalling
    • H04L2025/03802—Signalling on the reverse channel

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Power Engineering (AREA)
  • Quality & Reliability (AREA)
  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Mobile Radio Communication Systems (AREA)
  • Monitoring And Testing Of Transmission In General (AREA)

Abstract

Method of estimating the quality of focusing of a signal pre-equalized by time reversal of an estimated propagation channel between an original antenna (A1) of an original communicating entity (EC1) and a destination antenna (A2) of a destination communicating entity (EC2), the method comprising a step of evaluating a quality of focusing (Qv , Qssessel, Qv, Qsym, Qsymp, QDS, QEQ) of the signal received on the destination antenna, with respect to a value, for a focal point (FO), of a representation (QUAL1, QUAL2) of a curve of power received as a function of a distance (L) between the destination antenna and the focal point.

Description

Estimate the method for quality of the gathering of the signal of preequalization by time reversal
Technical field
The field of the invention is a field of telecommunications, and more accurately, is the field of the radio communication technology between the communication entity.
The present invention relates more specifically to the quality based on the transmission of signal between two communication entities of time reversal technology.
Background technology
Experienced distortion by the radio signal that antenna transmitted of communication entity as the function of the propagation conditions between the source point of the output place definition of source antenna and point of destination in the input definition of the antenna of purpose communication entity.In order to limit this distortion, make the aerial signal predistortion by using pre-equalization coefficients as the function of the characteristic of the propagation channel between these two antennas.Therefore, must characterize this propagation channel.
Among existing pre-equalisation method, the method for inverting service time is because complexity, its performance of its minimizing and be used for radio wave assembled (focus) capability to the reception antenna and noticeable.Time reversal makes may be by assembling the time dispersive (temporal dispersion) that reduces propagation channel significantly to the energy of received signal in time and spatially.
Time reversal is a kind of technology consistency of wave equation in time reversal, that be used to assemble ripple (typically, sound wave) that depends on.Thereby the ripple of time reversal is propagated as the forward wave that advances to reversion in time.Propagate propagation medium from the short pulse that source point sends.The part of this ripple that is received by point of destination is carried out time reversal to postbacking before sending in propagation medium.Assemble towards source point to postbacking the ripple that send, it forms short pulse there, and the energy of this ripple is collected on the source point.The shape that accumulates in the signal on the source point by time reversal is consistent in fact with the shape of the source signal that sends at the source point place.Thereby, recompress at source point place time of occurrence.Particularly, propagation medium is complicated more, and the ripple of time reversal is assembled accurately more.
Therefore, in radio circuit, use the time reversal technology, eliminating the effect of propagation channel by the expansion that reduces channel especially, and be reduced at the processing of passing the code element that receives after this channel for this signal.Thereby the coefficient that time reversal obtains is carried out in the impulse response of the propagation channel that the aerial signal that the antenna by the sources traffic entity is sent by application must pass, and comes this signal is carried out preequalization.Make to the time reversal of the propagation channel of this signal application and may eliminate this channel, and this signal is accumulated on the purpose antenna effect from the transmission of the source point of the signal of such predistortion.Therefore, time reversal needs the sources traffic entity to have the knowledge of propagation channel.
Yet, if communication entity moves because the mobility of communication entity, so by communication entity preset time channel estimating that the place produces time after a while the place may prove wrong.Come this error is carried out measurement verification (qualify) with respect to defined relative motion, this defined relative motion as from the function of the motion of the sources traffic entity of purpose communication entity observation.For big relative motion, between the estimation of the propagation channel that is used for signal is carried out predistortion and the actual propagation channel that passes of this signal, there is decorrelation.Do not have this signal is accumulated on the antenna of purpose communication entity, and the power of the signal that receives is lower than when not having relative motion the power of the signal that will receive.
In fact, signal postpones (latency delay) generation at defocus (defocus) at purpose antenna place by relative motion and stand-by period.The stand-by period delay is processing delay and the transmission of preequalization signal and the total delay of the delay between the reception that comprises between the transmission of the measurement of propagation channel and preequalization signal.
The purpose antenna with respect to the location definition of the estimation of the propagation channel of preequalization signal application focus.Therefore, focus is corresponding to the position of purpose antenna before postponing in the stand-by period with respect to source antenna.In other words, focus is corresponding at fixing communication entity with there is not the convergent point of the ripple under the stand-by period delay situation.If in one of two communication entities of stand-by period timing period or both motions, then the purpose antenna is in the position different with respect to the position of source antenna with focus, and therefore, does not pay close attention to (respect) focus.
If it is signal is not assembled, then quality-degraded.For example, service quality is the data rate supplied or by the error rate of the data of signal conveys.Thereby in case purpose communication entity and/or the motion of sources traffic entity, service quality just worsens.This worsens along with increasing and increase in the motion of stand-by period time durations sources traffic entity with respect to the purpose communication entity.In other words, if increase in stand-by period time durations relative motion, the power that then receives at purpose antenna place reduces.In addition, this deterioration is the function of the carrier frequency of preequalization signal.
Therefore, must carry out measurement verification to aggregate quality.
Summary of the invention
In order to realize this target, the invention provides a kind of method of aggregate quality of estimated signal, this signal by the sources traffic entity source antenna and the time reversal of the estimated propagation channel between the purpose antenna of purpose communication entity come preequalization, described communication entity can carry out relative motion.This method of estimation comprises and is evaluated at signal that purpose antenna place the receives step with respect to the aggregate quality of the value at the focus place of the expression (representation) of the curve of received power, the function that is expressed as the distance between purpose antenna and the focus of this received power curve, described focus is corresponding to the position of described purpose antenna before postponing in the stand-by period with respect to described source antenna.
Therefore, the method makes and may estimate aggregate quality by attribute by at the transmission signal operate time inversion procedure of any frequency empty the time.Thereby, expressed aggregate quality with respect to the biggest quality that must realize in focus, and do not had this aggregate quality is expressed as the absolute mass that depends on the signal carrier frequency.Focus is corresponding to the position of purpose antenna before postponing in the stand-by period with respect to source antenna.Estimating with respect to the position of focus that aggregate quality makes based on the purpose antenna may be simply and quality of evaluation apace.
The expression of this received power curve is the decreasing function of the distance between purpose antenna and the focus.
Thereby the expression of received power curve has been expressed by one or whole two communication entities mass change that motion produced at the stand-by period timing period.
Assess aggregate quality based on the sources traffic entity with respect to the assessment of the motion of purpose communication entity.
Thereby aggregate quality is easy to assessment, and need not by given purpose antenna with respect to the situation of the motion of focus under deterioration on the evaluation of signal quality measure the power of received signal.
Thereby directly carrier frequency by this signal and sources traffic entity provide aggregate quality with respect to the estimation of the motion of purpose communication entity.
Can also assess aggregate quality based on the symmetric estimation of the time of received signal.
Thereby, come processing signals by the fast method that utilizes relative low-complexity, assess this quality.
Can also assess aggregate quality based on the time symmetry and the symmetric estimation of power of received signal.
Thereby, jointly use the temporal information and the power information of received signal, the accuracy that makes the assessment that may increase aggregate quality.
Can be based on the temporal extension factor of the signal that receives via the purpose antenna with respect to reference signal in the estimation of the temporal extension factor at focus place or based on the autocorrelative estimation of propagation channel, assess aggregate quality.
Two kinds of assessments of this of aggregate quality are for the synchronous error relative insensitivity in the signal that is received by the purpose communication entity.Two kinds of assessments of this of aggregate quality comprise that also the purpose antenna receives the step of the pulse that is transmitted by source antenna.Thereby the pulse data that is received makes it possible to carry out the comparison of the estimation of the channel impulse response carried out at the different time place, and thereby makes and may increase the accuracy of assessment.
The present invention also provides a kind of device that is used for the aggregate quality of estimated signal, this signal by the sources traffic entity source antenna and the time reversal of the estimated propagation channel between the purpose antenna of purpose communication entity come preequalization, described communication entity can carry out relative motion.This device comprises evaluator, be used to be evaluated at signal that purpose antenna place receives aggregate quality with respect to the value at the focus place of the expression of the curve of received power, the function that is expressed as the distance between purpose antenna and the focus of this received power curve, described focus is corresponding to the position of described purpose antenna before postponing in the stand-by period with respect to described source antenna.
The invention still further relates to a kind of communication entity of radio communications system, comprise the above device that is used to estimate aggregate quality.
The present invention also provides a kind of radio communications system, comprises at least one communication entity of the present invention.
Described device, this communication entity and this system have and above-mentioned advantage confers similar advantages.
Description of drawings
In case only read by means of illustrative and non-limiting example provide, the following description of specific embodiments of the invention and the communication entity that is associated, and with reference to the accompanying drawings, it is obviously clear more that other features and advantages of the present invention just become, wherein:
Fig. 1 is the block diagram of the sources traffic entity that communicates with the purpose communication entity of a realization according to the present invention;
Fig. 2 has represented the example as the expression of the curve of the received power of the function of distance between purpose antenna and the focus;
Fig. 3 has represented the example that the normalization of received power curve is represented;
Fig. 4,5,6,7 and 8 has represented the step of the assessment aggregate quality in the different realizations of the present invention.
Embodiment
For the sake of clarity, to the one-way transmission of purpose communication entity EC2 the present invention is described from communication entity EC1 at data-signal.The present invention relates to two-way transmission equally, and the communication entity that comprises a plurality of transmission or reception antenna is provided.
With reference to figure 1, communication entity EC1 can come to communicate with destination entity EC2 via the radio circuit that does not have expression in the figure.
For example, radio circuit is as UMTS (Universal Mobile Telecommunications System) cellular radio that is defined by 3GPP (third generation partner program) tissue and its evolution or WIMAX (World Interoperability for Microwave Access, WiMax) radio circuit that comprises 3GPP-LTE (LTE has represented " Long Term Evolution ").
Communication entity can be portable terminal, ground or satellite base station, access point or any equipment that is equipped with communication card.
Sources traffic entity EC1 can be at carrier frequency f pGo up from antenna A 1To purpose communication entity EC2 data signal.
Purpose communication entity EC2 is suitable for the antenna A at the purpose communication entity 2The place receives data-signal, and from the signal that receives restore data.
By using the estimating impulse response h of time reversal Rt(t) coefficient comes data-signal is carried out pre-filtering.The antenna A of sources traffic entity has been represented in impulse response 1The antenna A of (being called source antenna) and purpose communication entity 2Propagation channel C between (being called the purpose antenna) (EC1 → EC2).
In tdd mode, be on the identical carrier frequency and carry out transmission (for example, from sources traffic entity EC1 to purpose communication entity EC2's) first direction and the transmission in the second direction opposite in the different time with first direction.Traditionally, estimate the impulse response of propagation channel based on the analysis of the signal that in second direction, transmits by sources traffic entity EC1.
In fdd mode, in different frequency bands, carry out in the first direction transmission and in the opposite direction in transmission.For example, can obtain the knowledge of the EC1 pair of propagation channel corresponding of sources traffic entity according to the estimation of the propagation channel of carrying out by purpose communication entity EC2 with first direction of transfer.
No matter what transfer mode is, sources traffic entity EC1 or purpose communication entity EC2 are thereby be suitable for propagation channel is estimated.Estimate that if carry out this then this entity is suitable for pre-equalization coefficients from the time reversal of this estimation to the sources traffic entity that transmit this estimation or obtained by by purpose communication entity EC2.
Postpone by time interval definition process, this time interval with the measurement of propagation channel and according to these measurements and the transmission of definite preequalization signal separately.Be added the transmission and the processing delay in the reception time interval separately that are used for the preequalization signal and determined that the stand-by period postpones D LThe stand-by period delay is the configuration parameter of communication entity.
Fig. 1 only shows the parts of purpose communication entity related to the present invention.Purpose communication entity EC2 also comprises the central control unit (not shown), the operation that it is connected to these parts and is suitable for controlling these parts.
The purpose communication entity comprises the signal that received by the purpose antenna with respect to the evaluator EVAL in the aggregate quality of the value at the focus place of the curve representation of received power, and the curve representation of this received power is the function of the distance between purpose antenna and the focus.
The determining of expression of received power curve described with reference to figure 2 and 3.
At purpose antenna A 2The power of the preequalization signal that the place receives has been determined this quality of signals, and thereby, determined service quality, for example data rate of being supplied or data error rate.When not having sources traffic entity EC1 and ought not exist any stand-by period to postpone D with respect to the motion v of purpose communication entity EC2 LThe time, the power of the signal of preequalization locates to be maximum at ripple at the convergent point (being called focus) at purpose antenna place by time reversal.Thereby focus is corresponding to the position of purpose antenna before postponing in the stand-by period with respect to source antenna.
If in stand-by period time durations communication entity motion, then this focus is no longer valid.This is crossed the border (transgression) be expressed as the stand-by period and postpone D LWith the function of sources traffic entity with respect to the motion v of purpose communication entity.Thereby, provide the position of purpose antenna and the distance between the focus by (for example, in the form of speed) relative motion v and the product of time stand-by period:
L＝v.D L
Below, relative motion v must be interpreted as motion as the sources traffic entity of seeing from the purpose communication entity.
If purpose sky line-spacing focus far away (for example because inappropriate stand-by period postpones or between the moving period of one or whole two communication entities), then power no longer is maximum.Fig. 2 has represented two examples as the expression of the curve of the received power of the function of distance between purpose antenna and the focus.With the preequalization signal at carrier frequency f 1On the function f ocal_1 of transmission correspondence be maximum at focal point F O place, and as reducing to the monotonic function of the distance L of focus.
The purpose antenna is at the position P at distance focal length L place A2The received power P at place 1Received power P less than the focus place FO, 1
The scope of received power curve and shape are the functions of propagation channel (carrier frequency of this signal especially).The expression of received power curve reduces along with carrier frequency and broadens.Thereby function f ocal_1 is corresponding to frequency f 1, this frequency f 1Along with carrier frequency f with respect to function f ocal_2 2Increase and reduce.
For example, at title " Signal Frequency and Bandwidth Effects on the Performance of UWB Time-Reversal Technique ", A.Khaleghi and G.El Klein, Loughborough Antennas and Propagation Conference, 2007, proved above attribute in the 97th to 100 page the article.
In the ordinary course of things, aggregate quality is carried out the expression that measurement verification can depend on the power curve of received signal, it has been expressed as to the variation of the quality of the function of the distance of focus and depend on the carrier frequency of this signal.This expression makes:
Reach its maximum at the focus place;
It is as the monotonic function of distance between purpose antenna and the focus and reduce.
Can consider that similarly the so-called normalization of received power curve represents that wherein maximum is identical for all carrier frequency.The normalization of received power curve represents it is monotonic decreasing function to the distance of focus, makes for the given distance L between purpose antenna and the focus, if Q 1And Q 2Be corresponding carrier frequency f 1And f 2Two value (wherein, f of aggregate quality 1Less than f 2), Q then 1Greater than Q 2Correspondingly, for the position P of purpose antenna at distance focal length L place A2, and at carrier frequency f 1The aggregate quality of uploading the feed signals correspondence greater than with at carrier frequency f 2Upload the aggregate quality of feed signals correspondence.
Fig. 3 shows the normalization of received power curve and represents, curve QUAL 1Corresponding in frequency f 1Last transmission preequalization signal, and curve QUAL 2Corresponding in frequency f 2Last transmission preequalization signal, wherein frequency f 1Less than frequency f 2
Below, based on estimation h by the paired pulses response RtAttribute is described the distinct methods of assessment aggregate quality when (t) carrying out gathering empty of the signal that time reversal carries out.Propagation channel C (the EC1 → EC2) between source antenna and the purpose antenna is represented in impulse response.The transfer function of the estimation of the impulse response of propagation channel is designated as H Rt(f).
By the signal aggregate quality that evaluator EVAL comes purpose of appraisals antenna place with respect to the value of the focus of the expression of received power, the function that is expressed as the distance between purpose antenna and the focus of this received power.Focus is corresponding to the position of purpose antenna before postponing in the stand-by period with respect to source antenna.
Begin with the signal that receives at purpose antenna place, described appraisal procedure is based on the estimation of relative motion, time or the temporal extension of symmetric assessment of power or received signal or the autocorrelative estimation of propagation channel of received signal.Then, with the focus actual position that does not need to know irrespectively and when not carrying out under the situation of measurement at the focus place, determine performance figure.
Be described with reference to Figure 4 first method of assessment aggregate quality.Assess aggregate quality according to the sources traffic entity with respect to the estimation of the motion of purpose communication entity.
In step e 1-1, the purpose communication entity is estimated the relative motion v of sources traffic entity.For example, relative motion is estimated in the position of the communication entity that can set up based on GPS (global positioning system) technology of using those skilled in the art to be familiar with.By means of non-limiting example, title is " The SMARTProject-Speed Measurement Validation in Real Traffic Conditions ", P.Bellucci, E.Cipriani, M.Gagliarducci and C.Riccucci, Proceedings of the 8th International IEEE Conference on Intelligent Transportation Systems, Vienna, Austria, September 13-16, paper in 2005 have described the method for measuring the relative motion of mobile system.
In step e 1-2, the purpose communication entity postpones D according to the stand-by period LThe distance L from the purpose antenna to focus is estimated in the estimation of (for example, in the velocity form) relative motion v, makes
L＝v.D L
In step e 1-3, the estimated distance to focus of communication entity use is estimated the aggregate quality Q with respect to the value at the focus place of the expression of received power curve vProvide aggregate quality by following formula:
Q v = ( λ / 2 ) - L ( λ / 2 )
Wherein, λ is the carrier frequency f by the preequalization signal of source antenna transmission pThe wavelength at place, and by λ=c/f pProvide, wherein cIt is the light velocity.
Alternatively, estimate aggregate quality Q by the reception power curve being carried out modeling based on zeroth order Bezier (Bessel) function that provides by following formula Bessel:
Q Bessel = Bessel ( L λ )
Be described with reference to Figure 5 second method of assessment aggregate quality.Assess aggregate quality based on the symmetric estimation of the time of received signal.For this reason, introduced the signal symmetry sex index.It is known that the signal of preequalization is on the time symmetry fully in focus by time reversal.This symmetry can't obtain outside focus, and asymmetry is along with to the distance of focus and increase.
In step e 2-1, communication entity calculates discrete Fourier (Fourier) conversion of the preequalization signal that receives via the purpose antenna, represents so that obtain this signal frequency-domain.Frequency domain representation S (the f of the data-signal s (t) that receives k) be plural number, and at from the total bandwidth B that distributes to the purpose communication entity ECAny carrier frequency f k, comprise S (f k) real part Re kAnd S (f k) imaginary part Im k
In step e 2-2, the purpose communication entity is at each the carrier frequency f that distributes to the purpose communication entity kAssess the symmetry index IND of the received signal that provides by following formula k:
IND k = Re k 2 ( Re k + Im k ) 2
In step e 2-3, that communication entity is determined to be provided by following formula, with respect to the aggregate quality Q of the value that is illustrated in the focus place of power curve Sym:
Q sym = Σ k = 1 N f IND k N f
Wherein, N fIndicated at wave band B ECIn the number of the carrier frequency that distributes to the purpose communication entity.
Be described with reference to Figure 6 third party's method of assessment aggregate quality.Aggregate quality is assessed in time symmetry and the symmetric estimation of power based on received signal.Compare with the asymmetry of locating to measure in another time, at time t MaxThe time asymmetry that the place is measured must be confronted measurer has bigger influence, this time t MaxCorresponding to the time of the energy of having concentrated this signal.In other words, the asymmetry at preset time place has more influences to total asymmetry of signal when the energy of this signal is bigger at this some place.
Reception time-domain signal based on sampling is assessed aggregate quality, and this receives time-domain signal at time t nThe sampling at place is indicated as s (t n).
In step e 3-1, communication entity is determined exponent m ax, makes this signals sampling s (t MaxValue be maximum.
In step e 3-2, communication entity at this signal of in step e 3-1, determining at time t MaxThe different time difference that the sampling at place is relevant is determined the time symmetry Sym of received signal t(n) N value:
Sym t ( n ) = | s ( t max + t n + max ) - s ( t max - t n + max ) | / 2 ( t n + max - t max ) / τ
Wherein, E is the energy of received signal, and τ is the temporal extension factor of estimated received signal.
The number N of symmetry value is the configurable parameter of purpose communication entity, and the accuracy of quality evaluation increases along with N.
For example, can use at paper " Delay Spread Estimation for Wireless Communications systems ", H ü seyin Arslan and Tevfik Y ü cek, Proceedings of the Eighth IEEE International Symposium on Computers and Communications, the method for describing in 2003 is come evaluation time spreading factor τ.
In step e 3-3, communication entity at respect to the signal of in step e 3-1, determining at time t MaxThe different time difference of the sampling at place is determined N symmetry value Sym of the power of received signal P(n):
Sym p ( n ) = [ | s ( t max + t n + max ) | 2 + | s ( t n max - t n + max ) | 2 ] / E 2 ( t n + max - t max ) / τ
In step e 3-4, that communication entity is determined to be provided by following formula, with respect to the aggregate quality Q of the value that is illustrated in the focus place of received power curve Symp:
Q symp = 1 N Σ n = 1 N ( π 2 / 4 ) - [ a tan ( Sym t ( n ) ) . a tan ( Sym p ( n ) ) ] π 2 / 4
Wherein, atan refers to the arctangent cp cp operation symbol.
Be described with reference to Figure 7 the cubic method of assessment aggregate quality.The temporal extension factor based on received signal is assessed aggregate quality with respect to reference signal in the estimation of the temporal extension at focus place.The also frequent in the literature temporal extension factor with signal is called and postpones expansion.
As at paper " Characterization of Space-Time Focusing in Time-Reversed Random Fields ", Claude Oestges, Arnold D.Kim, George Papanicolaou and Arogyaswami J.Paulraj, IEEE Transactions on Antennas and Propagation, the 53rd volume, demonstration in 2005 1 month, the attribute of spreading factor is that it is along with reducing to the distance of focus.
In step e 4-1, the sources traffic entity transmits pulse to the purpose communication entity.Thereby this entity receives the impulse response h of the propagation channel between source entity and the destination entity c(t), the ground that perhaps comes to the same thing, the transfer function H of estimation propagation channel c(f).
In step e 4-2, the purpose communication entity for example uses at paper " Delay Spread Estimation for Wireless Communications systems ", H ü seyin Arslan and Tevfik Y ü cek, Proceedings of the Eighth IEEE International Sympo sium on Computers and Communications, the method for describing in 2003 is measured the temporal extension factor D Ssig of received signal.
In step e 4-3, the temporal extension factor D S of the reference signal ref (t) that the pulse that purpose communication entity assessment basis receives during step e 4-1 is constructed Ref, used the time reversal of impulse response that is used for this signal is carried out the propagation channel of preequalization to this reference signal ref (t) and estimated h Rt(t).In frequency domain, thereby provide this reference signal by following formula:
REF(f)＝H rt(f)*H c(f)
In step e 4-4, that communication entity is determined to be provided by following formula, with respect to the aggregate quality Q of the value that is illustrated in the focus place of received power curve DS:
Q DS = DS ref DS sig
Be described with reference to Figure 8 the 5th method of assessment aggregate quality.Assess aggregate quality based on the ratio between the power of the power of received signal and reference signal.This power ratio has been represented the autocorrelative estimation of propagation channel.
In step e 5-1, the sources traffic entity transmits pilot signal or pulse to the purpose communication entity, and it is used to estimate the impulse response h of the propagation channel between sources traffic entity and the purpose communication entity c(t), the ground that perhaps comes to the same thing, the transfer function H of estimation propagation channel c(f).
In step e 5-2, the purpose communication entity is determined the power of propagation channel.For example, any power assessments method of being familiar with by those skilled in the art, the power P of assessing propagation channel with respect to the bandwidth B and the bandwidth W (B) of this signal c:
P c = 1 W ( B ) ∫ f ∈ B | | H c ( f ) * × H c ( f ) | | 2
In step e 5-3, the purpose communication entity carries out demodulation to the preequalization signal that receives at purpose antenna place, and estimates the transfer function H by propagation channel Rt(f) conjugation and transfer function H c(f) product provides, the propagation channel of equivalence:
H eq(f)＝H rt(f) *H c(f)
This transfer function H Rt(f) corresponding to being used for to transmitting the impulse response h that signal carries out preequalization Rt(f).
In step e 5-4, communication entity is determined the power P of equivalent channel EqFor example, assess the power of equivalent channel with respect to the big or small W (B) of the bandwidth B of this signal and bandwidth:
P eq = 1 W ( B ) ∫ f ∈ B | | Heq ( f ) | | 2
In step e 5-5, that the purpose communication entity is determined to be provided by following formula, with respect to the aggregate quality Q of the value that is illustrated in the focus place of received power curve EQ:
Q EQ = | | P eq | | 2 | | P c | | 2
Alternatively, assess aggregate quality by making up above-mentioned different measuring.Correspondingly, consider respectively based on the auto-correlation of symmetric estimation of time, time symmetry and the symmetric estimation of power, the temporal extension factor and the channel of relative motion and wavelength, relative motion and Bessel function, received signal and the Q that defines v, Q Bessel, Q Sym, Q Symp, Q DS, and Q EQAssessment, by using assessment Q v, Q Bessel, Q Sym, Q Symp, Q DS, and Q EQThe combination monotonically increasing function obtain aggregate quality.
Described hereinly the present invention relates to a kind of device that is used to estimate aggregate quality that in communication entity, uses.As a result, the present invention is equally applicable to a kind of computer program, especially, a kind of be suitable for realizing of the present invention, on information storage medium or in computer program.This program can be used any programming language, and take the form of source code, object code or (the compiling form) code between source code and object code or take to be suitable for to be implemented in any other forms of those steps of the inventive method of carrying out in the purpose communication entity such as, part.

Claims (12)

1. the method for the aggregate quality of an estimated signal, this signal is by the source antenna (A at sources traffic entity (EC1) 1) with the purpose antenna (A of purpose communication entity (EC2) 2) between the time reversal of estimated propagation channel come preequalization, described communication entity can carry out relative motion;
Described method is characterised in that, described method comprises and is evaluated at signal that purpose antenna place the receives curve (QUAL with respect to received power 1, QUAL 2) the aggregate quality (Q of the value located of the focus (FO) of expression v, Q Bessel, Q Sym, Q Symp, Q DS, Q EQ) step, the function that is expressed as the distance (L) between purpose antenna and the focus of this received power curve, described focus corresponding to described purpose antenna before the stand-by period postpones with respect to the position of described source antenna.
2. according to the process of claim 1 wherein that the expression of this received power curve is the decreasing function of the distance between purpose antenna and the focus.
3. according to the method for claim 1 or claim 2, wherein (aggregate quality (Q is assessed in assessment v) with respect to the motion of purpose communication entity based on the sources traffic entity v, Q Bessel).
4. according to the method for claim 1 or claim 2, wherein assess aggregate quality (Q based on the symmetric estimation of the time of received signal Sym).
5. according to the method for claim 1 or claim 2, wherein assess aggregate quality (Q based on the time symmetry and the symmetric estimation of power of received signal Symp).
6. according to the method for claim 1 or claim 2, wherein assess aggregate quality (Q with respect to reference signal in the estimation of the temporal extension factor at focus place based on the temporal extension factor of the signal that receives by the purpose antenna DS).
7. according to the method for claim 1 or claim 2, wherein assess aggregate quality (Q based on the autocorrelative estimation of propagation channel EQ).
8. according to the method for claim 6 or claim 7, wherein the assessment of aggregate quality comprises that also the purpose antenna receives the step of the pulse that is transmitted by source antenna.
9. device that is used for the aggregate quality of estimated signal, this signal is by the source antenna (A at sources traffic entity (EC1) 1) with the purpose antenna (A of purpose communication entity (EC2) 2) between the time reversal of estimated propagation channel come preequalization, described communication entity can carry out relative motion; Described device is characterised in that described device comprises evaluator (EVAL), is used to be evaluated at signal that purpose antenna place the receives curve (QUAL with respect to received power 1, QUAL 2) the aggregate quality (Q of the value located of the focus (FO) of expression v, Q Bessel, Q Sym, Q Symp, Q DS, Q EQ), the function that is expressed as the distance (L) between purpose antenna and the focus of this received power curve, described focus is corresponding to the position of described purpose antenna before postponing in the stand-by period with respect to described source antenna.
10. the communication entity of a radio communications system comprises the device according to claim 9.
11. a radio communications system comprises at least one communication entity according to claim 10.
12. a computer program that is used for communication entity comprises when carrying out this program by this communication entity, is used for order and is carried out according to each the software instruction of those steps of method of claim 1 to 8 by described entity.
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